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/** @import { Context, Visitor, Visitors } from 'zimmerframe' */
/** @import { AnimateDirective, Binding, DeclarationKind, EachBlock, ElementLike, LetDirective, SvelteNode, TransitionDirective, UseDirective } from '#compiler' */
import is_reference from 'is-reference';
import { walk } from 'zimmerframe';
import { is_element_node } from './nodes.js';
import * as b from '../utils/builders.js';
import * as e from '../errors.js';
import {
extract_identifiers,
extract_identifiers_from_destructuring,
object,
unwrap_pattern
} from '../utils/ast.js';
import { JsKeywords, Runes } from './constants.js';
export class Scope {
/** @type {ScopeRoot} */
root;
/**
* The immediate parent scope
* @type {Scope | null}
*/
parent;
/**
* Whether or not `var` declarations are contained by this scope
* @type {boolean}
*/
#porous;
/**
* A map of every identifier declared by this scope, and all the
* identifiers that reference it
* @type {Map<string, Binding>}
*/
declarations = new Map();
/**
* A map of declarators to the bindings they declare
* @type {Map<VariableDeclarator | LetDirective, Binding[]>}
*/
declarators = new Map();
/**
* A set of all the names referenced with this scope
* — useful for generating unique names
* @type {Map<string, { node: Identifier; path: SvelteNode[] }[]>}
*/
references = new Map();
/**
* The scope depth allows us to determine if a state variable is referenced in its own scope,
* which is usually an error. Block statements do not increase this value
*/
function_depth = 0;
/**
*
* @param {ScopeRoot} root
* @param {Scope | null} parent
* @param {boolean} porous
*/
constructor(root, parent, porous) {
this.root = root;
this.parent = parent;
this.#porous = porous;
this.function_depth = parent ? parent.function_depth + (porous ? 0 : 1) : 0;
}
/**
* @param {Identifier} node
* @param {Binding['kind']} kind
* @param {DeclarationKind} declaration_kind
* @param {null | Expression | FunctionDeclaration | ClassDeclaration | ImportDeclaration | EachBlock} initial
* @returns {Binding}
*/
declare(node, kind, declaration_kind, initial = null) {
if (node.name === '$') {
e.dollar_binding_invalid(node);
}
if (
node.name.startsWith('$') &&
declaration_kind !== 'synthetic' &&
declaration_kind !== 'param' &&
declaration_kind !== 'rest_param' &&
this.function_depth <= 1
) {
e.dollar_prefix_invalid(node);
}
if (this.parent) {
if (declaration_kind === 'var' && this.#porous) {
return this.parent.declare(node, kind, declaration_kind);
}
if (declaration_kind === 'import') {
return this.parent.declare(node, kind, declaration_kind, initial);
}
}
if (this.declarations.has(node.name)) {
// This also errors on var/function types, but that's arguably a good thing
e.declaration_duplicate(node, node.name);
}
/** @type {Binding} */
const binding = {
node,
references: [],
legacy_dependencies: [],
initial,
mutated: false,
scope: this,
kind,
declaration_kind,
is_called: false,
prop_alias: null,
mutation: null,
reassigned: false,
metadata: null
};
this.declarations.set(node.name, binding);
this.root.conflicts.add(node.name);
return binding;
}
child(porous = false) {
return new Scope(this.root, this, porous);
}
/**
* @param {string} preferred_name
* @returns {string}
*/
generate(preferred_name) {
if (this.#porous) {
return /** @type {Scope} */ (this.parent).generate(preferred_name);
}
preferred_name = preferred_name.replace(/[^a-zA-Z0-9_$]/g, '_').replace(/^[0-9]/, '_');
let name = preferred_name;
let n = 1;
while (
this.references.has(name) ||
this.declarations.has(name) ||
this.root.conflicts.has(name) ||
JsKeywords.includes(name)
) {
name = `${preferred_name}_${n++}`;
}
this.references.set(name, []);
this.root.conflicts.add(name);
return name;
}
/**
* @param {string} name
* @returns {Binding | null}
*/
get(name) {
return this.declarations.get(name) ?? this.parent?.get(name) ?? null;
}
/**
* @param {VariableDeclarator | LetDirective} node
* @returns {Binding[]}
*/
get_bindings(node) {
const bindings = this.declarators.get(node);
if (!bindings) {
throw new Error('No binding found for declarator');
}
return bindings;
}
/**
* @param {string} name
* @returns {Scope | null}
*/
owner(name) {
return this.declarations.has(name) ? this : this.parent && this.parent.owner(name);
}
/**
* @param {Identifier} node
* @param {SvelteNode[]} path
*/
reference(node, path) {
path = [...path]; // ensure that mutations to path afterwards don't affect this reference
let references = this.references.get(node.name);
if (!references) this.references.set(node.name, (references = []));
references.push({ node, path });
const binding = this.declarations.get(node.name);
if (binding) {
binding.references.push({ node, path });
} else if (this.parent) {
this.parent.reference(node, path);
} else {
// no binding was found, and this is the top level scope,
// which means this is a global
this.root.conflicts.add(node.name);
}
}
}
export class ScopeRoot {
/** @type {Set<string>} */
conflicts = new Set();
/**
* @param {string} preferred_name
*/
unique(preferred_name) {
preferred_name = preferred_name.replace(/[^a-zA-Z0-9_$]/g, '_');
let final_name = preferred_name;
let n = 1;
while (this.conflicts.has(final_name)) {
final_name = `${preferred_name}_${n++}`;
}
this.conflicts.add(final_name);
const id = b.id(final_name);
return id;
}
}
/**
* @param {SvelteNode} ast
* @param {ScopeRoot} root
* @param {boolean} allow_reactive_declarations
* @param {Scope | null} parent
*/
export function create_scopes(ast, root, allow_reactive_declarations, parent) {
/** @typedef {{ scope: Scope }} State */
/**
* A map of node->associated scope. A node appearing in this map does not necessarily mean that it created a scope
* @type {Map<SvelteNode, Scope>}
*/
const scopes = new Map();
const scope = new Scope(root, parent, false);
scopes.set(ast, scope);
/** @type {State} */
const state = { scope };
/** @type {[Scope, { node: Identifier; path: SvelteNode[] }][]} */
const references = [];
/** @type {[Scope, Pattern | MemberExpression][]} */
const updates = [];
/**
* An array of reactive declarations, i.e. the `a` in `$: a = b * 2`
* @type {Identifier[]}
*/
const possible_implicit_declarations = [];
/**
* @param {Scope} scope
* @param {Pattern[]} params
*/
function add_params(scope, params) {
for (const param of params) {
for (const node of extract_identifiers(param)) {
scope.declare(node, 'normal', param.type === 'RestElement' ? 'rest_param' : 'param');
}
}
}
/**
* @type {Visitor<Node, State, SvelteNode>}
*/
const create_block_scope = (node, { state, next }) => {
const scope = state.scope.child(true);
scopes.set(node, scope);
next({ scope });
};
/**
* @type {Visitor<ElementLike, State, SvelteNode>}
*/
const SvelteFragment = (node, { state, next }) => {
const [scope] = analyze_let_directives(node, state.scope);
scopes.set(node, scope);
next({ scope });
};
/**
* @param {ElementLike} node
* @param {Scope} parent
*/
function analyze_let_directives(node, parent) {
const scope = parent.child();
let is_default_slot = true;
for (const attribute of node.attributes) {
if (attribute.type === 'LetDirective') {
/** @type {Binding[]} */
const bindings = [];
scope.declarators.set(attribute, bindings);
// attach the scope to the directive itself, as well as the
// contents to which it applies
scopes.set(attribute, scope);
if (attribute.expression) {
for (const id of extract_identifiers_from_destructuring(attribute.expression)) {
const binding = scope.declare(id, 'derived', 'const');
bindings.push(binding);
}
} else {
/** @type {Identifier} */
const id = {
name: attribute.name,
type: 'Identifier',
start: attribute.start,
end: attribute.end
};
const binding = scope.declare(id, 'derived', 'const');
bindings.push(binding);
}
} else if (attribute.type === 'Attribute' && attribute.name === 'slot') {
is_default_slot = false;
}
}
return /** @type {const} */ ([scope, is_default_slot]);
}
/**
* @type {Visitor<AnimateDirective | TransitionDirective | UseDirective, State, SvelteNode>}
*/
const SvelteDirective = (node, { state, path, visit }) => {
state.scope.reference(b.id(node.name.split('.')[0]), path);
if (node.expression) {
visit(node.expression);
}
};
walk(ast, state, {
// references
Identifier(node, { path, state }) {
const parent = path.at(-1);
if (parent && is_reference(node, /** @type {Node} */ (parent))) {
references.push([state.scope, { node, path: path.slice() }]);
}
},
LabeledStatement(node, { path, next }) {
if (path.length > 1 || !allow_reactive_declarations) return next();
if (node.label.name !== '$') return next();
// create a scope for the $: block
const scope = state.scope.child();
scopes.set(node, scope);
if (
node.body.type === 'ExpressionStatement' &&
node.body.expression.type === 'AssignmentExpression'
) {
for (const id of extract_identifiers(node.body.expression.left)) {
if (!id.name.startsWith('$')) {
possible_implicit_declarations.push(id);
}
}
}
next({ scope });
},
SvelteFragment,
SlotElement: SvelteFragment,
SvelteElement: SvelteFragment,
RegularElement: SvelteFragment,
Component(node, { state, visit, path }) {
state.scope.reference(b.id(node.name), path);
// let:x is super weird:
// - for the default slot, its scope only applies to children that are not slots themselves
// - for named slots, its scope applies to the component itself, too
const [scope, is_default_slot] = analyze_let_directives(node, state.scope);
if (is_default_slot) {
for (const attribute of node.attributes) {
visit(attribute);
}
} else {
scopes.set(node, scope);
for (const attribute of node.attributes) {
visit(attribute, { ...state, scope });
}
}
for (const child of node.fragment.nodes) {
if (
is_element_node(child) &&
child.attributes.some(
(attribute) => attribute.type === 'Attribute' && attribute.name === 'slot'
)
) {
// <div slot="..."> inherits the scope above the component unless the component is a named slot itself, because slots are hella weird
scopes.set(child, is_default_slot ? state.scope : scope);
visit(child, { scope: is_default_slot ? state.scope : scope });
} else {
if (child.type === 'ExpressionTag') {
// expression tag is a special case — we don't visit it directly, but via process_children,
// so we need to set the scope on the expression rather than the tag itself
scopes.set(child.expression, scope);
} else {
scopes.set(child, scope);
}
visit(child, { scope });
}
}
},
// updates
AssignmentExpression(node, { state, next }) {
updates.push([state.scope, node.left]);
next();
},
UpdateExpression(node, { state, next }) {
updates.push([state.scope, /** @type {Identifier | MemberExpression} */ (node.argument)]);
next();
},
ImportDeclaration(node, { state }) {
for (const specifier of node.specifiers) {
state.scope.declare(specifier.local, 'normal', 'import', node);
}
},
FunctionExpression(node, { state, next }) {
const scope = state.scope.child();
scopes.set(node, scope);
if (node.id) scope.declare(node.id, 'normal', 'function');
add_params(scope, node.params);
next({ scope });
},
FunctionDeclaration(node, { state, next }) {
if (node.id) state.scope.declare(node.id, 'normal', 'function', node);
const scope = state.scope.child();
scopes.set(node, scope);
add_params(scope, node.params);
next({ scope });
},
ArrowFunctionExpression(node, { state, next }) {
const scope = state.scope.child();
scopes.set(node, scope);
add_params(scope, node.params);
next({ scope });
},
ForStatement: create_block_scope,
ForInStatement: create_block_scope,
ForOfStatement: create_block_scope,
BlockStatement: create_block_scope,
SwitchStatement: create_block_scope,
ClassDeclaration(node, { state, next }) {
if (node.id) state.scope.declare(node.id, 'normal', 'let', node);
next();
},
VariableDeclaration(node, { state, path, next }) {
const is_parent_const_tag = path.at(-1)?.type === 'ConstTag';
for (const declarator of node.declarations) {
/** @type {Binding[]} */
const bindings = [];
state.scope.declarators.set(declarator, bindings);
for (const id of extract_identifiers(declarator.id)) {
const binding = state.scope.declare(
id,
is_parent_const_tag ? 'derived' : 'normal',
node.kind,
declarator.init
);
bindings.push(binding);
}
}
next();
},
CatchClause(node, { state, next }) {
if (node.param) {
const scope = state.scope.child(true);
scopes.set(node, scope);
for (const id of extract_identifiers(node.param)) {
scope.declare(id, 'normal', 'let');
}
next({ scope });
} else {
next();
}
},
EachBlock(node, { state, visit }) {
// Array part is still from the scope above
/** @type {Set<Identifier>} */
const references_within = new Set();
const idx = references.length;
visit(node.expression);
for (let i = idx; i < references.length; i++) {
const [scope, { node: id }] = references[i];
if (scope === state.scope) {
references_within.add(id);
}
}
scopes.set(node.expression, state.scope);
// context and children are a new scope
const scope = state.scope.child();
scopes.set(node, scope);
// declarations
for (const id of extract_identifiers(node.context)) {
const binding = scope.declare(id, 'each', 'const');
let inside_rest = false;
let is_rest_id = false;
walk(node.context, null, {
Identifier(node) {
if (inside_rest && node === id) {
is_rest_id = true;
}
},
RestElement(_, { next }) {
const prev = inside_rest;
inside_rest = true;
next();
inside_rest = prev;
}
});
binding.metadata = { inside_rest: is_rest_id };
}
if (node.context.type !== 'Identifier') {
scope.declare(b.id('$$item'), 'derived', 'synthetic');
}
// Visit to pick up references from default initializers
visit(node.context, { scope });
if (node.index) {
const is_keyed =
node.key &&
(node.key.type !== 'Identifier' || !node.index || node.key.name !== node.index);
scope.declare(b.id(node.index), is_keyed ? 'derived' : 'normal', 'const', node);
}
if (node.key) visit(node.key, { scope });
// children
for (const child of node.body.nodes) {
visit(child, { scope });
}
if (node.fallback) visit(node.fallback, { scope });
// Check if inner scope shadows something from outer scope.
// This is necessary because we need access to the array expression of the each block
// in the inner scope if bindings are used, in order to invalidate the array.
let needs_array_deduplication = false;
for (const [name] of scope.declarations) {
if (state.scope.get(name) !== null) {
needs_array_deduplication = true;
}
}
node.metadata = {
keyed: false,
contains_group_binding: false,
array_name: needs_array_deduplication ? state.scope.root.unique('$$array') : null,
index: scope.root.unique('$$index'),
item: node.context.type === 'Identifier' ? node.context : b.id('$$item'),
declarations: scope.declarations,
references: [...references_within]
.map((id) => /** @type {Binding} */ (state.scope.get(id.name)))
.filter(Boolean),
is_controlled: false
};
},
AwaitBlock(node, context) {
context.visit(node.expression);
if (node.pending) {
context.visit(node.pending);
}
if (node.then) {
context.visit(node.then);
if (node.value) {
const then_scope = /** @type {Scope} */ (scopes.get(node.then));
const value_scope = context.state.scope.child();
scopes.set(node.value, value_scope);
context.visit(node.value, { scope: value_scope });
for (const id of extract_identifiers(node.value)) {
then_scope.declare(id, 'derived', 'const');
value_scope.declare(id, 'normal', 'const');
}
}
}
if (node.catch) {
context.visit(node.catch);
if (node.error) {
const catch_scope = /** @type {Scope} */ (scopes.get(node.catch));
const error_scope = context.state.scope.child();
scopes.set(node.error, error_scope);
context.visit(node.error, { scope: error_scope });
for (const id of extract_identifiers(node.error)) {
catch_scope.declare(id, 'derived', 'const');
error_scope.declare(id, 'normal', 'const');
}
}
}
},
SnippetBlock(node, context) {
const state = context.state;
// Special-case for root-level snippets: they become part of the instance scope
const is_top_level = !context.path.at(-2);
let scope = state.scope;
if (is_top_level) {
scope = /** @type {Scope} */ (parent);
}
scope.declare(node.expression, 'normal', 'function', node.expression);
const child_scope = state.scope.child();
scopes.set(node, child_scope);
for (const param of node.parameters) {
for (const id of extract_identifiers(param)) {
child_scope.declare(id, 'snippet', 'let');
}
}
context.next({ scope: child_scope });
},
Fragment: (node, context) => {
const scope = context.state.scope.child(node.transparent);
scopes.set(node, scope);
context.next({ scope });
},
BindDirective(node, context) {
updates.push([
context.state.scope,
/** @type {Identifier | MemberExpression} */ (node.expression)
]);
context.next();
},
TransitionDirective: SvelteDirective,
AnimateDirective: SvelteDirective,
UseDirective: SvelteDirective,
// using it's own function instead of `SvelteDirective` because
// StyleDirective doesn't have expressions and are generally already
// handled by `Identifier`. This is the special case for the shorthand
// eg <button style:height /> where the variable has the same name of
// the css property
StyleDirective(node, { path, state, next }) {
if (node.value === true) {
state.scope.reference(b.id(node.name), path);
}
next();
}
// TODO others
});
for (const id of possible_implicit_declarations) {
const binding = scope.get(id.name);
if (binding) continue; // TODO can also be legacy_reactive if declared outside of reactive statement
scope.declare(id, 'legacy_reactive', 'let');
}
// we do this after the fact, so that we don't need to worry
// about encountering references before their declarations
for (const [scope, { node, path }] of references) {
scope.reference(node, path);
}
for (const [scope, node] of updates) {
if (node.type === 'MemberExpression') {
let object = node.object;
while (object.type === 'MemberExpression') {
object = object.object;
}
const binding = scope.get(/** @type {Identifier} */ (object).name);
if (binding) binding.mutated = true;
} else {
unwrap_pattern(node).forEach((node) => {
let id = node.type === 'Identifier' ? node : object(node);
if (id === null) return;
const binding = scope.get(id.name);
if (binding && id !== binding.node) {
binding.mutated = true;
binding.reassigned = node.type === 'Identifier';
}
});
}
}
return {
scope,
scopes
};
}
/**
* @template {{ scope: Scope }} State
* @param {Map<SvelteNode, Scope>} scopes
* @returns {Visitors<SvelteNode, State>}
*/
export function set_scope(scopes) {
return {
/**
*
* @param {SvelteNode} node
* @param {Context<SvelteNode, State>} context
*/
_(node, { next, state }) {
const scope = scopes.get(node);
next(scope !== undefined && scope !== state.scope ? { ...state, scope } : state);
}
};
}
/**
* Returns the name of the rune if the given expression is a `CallExpression` using a rune.
* @param {Node | EachBlock | null | undefined} node
* @param {Scope} scope
* @returns {Runes[number] | null}
*/
export function get_rune(node, scope) {
if (!node) return null;
if (node.type !== 'CallExpression') return null;
let n = node.callee;
let joined = '';
while (n.type === 'MemberExpression') {
if (n.computed) return null;
if (n.property.type !== 'Identifier') return null;
joined = '.' + n.property.name + joined;
n = n.object;
}
if (n.type === 'CallExpression' && n.callee.type === 'Identifier') {
joined = '()' + joined;
n = n.callee;
}
if (n.type !== 'Identifier') return null;
joined = n.name + joined;
if (!Runes.includes(/** @type {any} */ (joined))) return null;
const binding = scope.get(n.name);
if (binding !== null) return null; // rune name, but references a variable or store
return /** @type {typeof Runes[number] | null} */ (joined);
}
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